Update cc icons and location they are served from

[obulat]

Fixes

Fixes #141 by @kgodey

Description

Updated the location from which icons that are embedded in html code are loaded from to https://mirrors.creativecommons.org. Also, I removed background circle from license icons so that they look better when the background is lighterGray.

Screenshots

With white background circle:

Without white background circle:

Checklist

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• I added tests for the changes I made (if applicable).
• I added or updated documentation (if applicable).
• I tried running the project locally and verified that there are no
  visible errors.

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